This invention relates to a downhole apparatus and method, including a packer or plug apparatus. More particularly, but not by way of limitation, this invention relates to an apparatus for a well packing device that can be partially removed downhole.
Generally in the prior art, well bore packing devices or plug devices use slip assemblies as a means to anchor the packing device to the tubular member of the well to be sealed off. The slip assemblies anchor the device within the well bore. Examples of prior-art packing devices are shown in U.S. Pat. No. 7,743,836, which is incorporated herein by reference in its entirety. Packers/plugs can be used for a variety of purposes, including placing a plug downhole in a “plug and abandon” procedure. One typical type of plug is called a cast iron bridge plug (CIBP), which is generally a tool that operates to seal against the well bore and is not designed to be retrievable or releasable from a set position. The CIBP is intended to be permanently positioned in the well bore at a desired location. Typical CIBPs are constructed of soft metal alloys, including high carbon steel, and also of composite synthetic materials. The running diameter of the plugs/packers are within close tolerances with the tubular for which it is designed to set and seal. This is necessary for the plug to be able to hold high differential pressures during the life cycle of the plug. This close tolerance can present problems in a well due to the presence of bends in the well tubing/casing or the presence of scale or other foreign matter that would serve to restrict the inner diameter of the well bore. In these instances, the plug can become lodged in the tubular during run-in at an unintended location and require removal.
Removal is accomplished via milling or drilling using a rig, snubbing unit, or coiled tubing unit. The removal process is time consuming and expensive, as the body of the plug contains a substantial amount of metal that must be drilled out. Some vendors have created plugs made from composite materials to reduce the time required to mill and remove the plug when compared to the metal alloy plugs.
As used herein:                i) The term plug refers to both packers (which allow flow through a center channel or bore of the packer) and plugs (which generally completely seal a tubular)        ii) The term “upward” refers to a direction toward the top of the well bore (the surface);        iii) The term “downward” refers to a direction toward the bottom of the well bore;        iv) The term “well bore” refers to an open hole, a cased well bore, or a well bore with a liner or tubing.        